Anharmonic lattice dynamics in type-I clathrates from first-principles calculations

被引：41

作者：

Madsen, GKH

Santi, G

机构：

[1] Aarhus Univ, Dept Chem, DK-8000 Aarhus C, Denmark

[2] Aarhus Univ, Dept Phys, DK-8000 Aarhus C, Denmark

来源：

PHYSICAL REVIEW B | 2005年 / 72卷 / 22期

关键词：

D O I：

10.1103/PhysRevB.72.220301

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The anharmonic lattice dynamics of (Sr/Ba)(8)Ga16+xGe30-x type-I clathrates are studied using first-principles calculations. The guest atoms in the large cages are found to lie in strongly anharmonic potentials, resulting in off-center (disordered) equilibrium positions for the Sr rattler. The lowest energy modes for Sr form a four level system with a tunneling splitting of only 0.04 meV. The thermodynamical properties and the inelastic neutron scattering spectra of the anharmonic rattlers are investigated.

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